1. Field of the Invention
The present invention relates to magnetism detecting devices that detect magnetism, for example, a magnetic azimuth detecting device suitable for obtaining at least three-axis geomagnetic azimuth information.
2. Description of the Related Art
In recent years, a magnetic azimuth detecting device referred to as electronic compass has been used in mobile terminal devices such as cellular phones and personal digital assistances (PDAs), in addition to a GPS (global positioning system), for example, for the reason that it is possible to obtain azimuth information whereby it is known in which direction a destination is (see, for example, Patent Document 1).
Conventional magnetic azimuth detecting devices will be described, taking as an example a magnetic azimuth detecting device that can detect geomagnetic azimuths of three axes of the X-axis, the Y-axis, and the Z-axis, that is, the front-back direction, the left-right direction, and the top-bottom direction, used in cellular phones.
FIG. 5 shows an example of a conventional magnetic azimuth detecting device. In a conventional magnetic azimuth detecting device 101, three magnetic sensors 103 and a control semiconductor device (control semiconductor package) 104 are mounted on one of the surfaces, the upper surface, of a square planar circuit substrate 102, and the three magnetic sensors 103 and the control semiconductor device 104 are encapsulated and integrated (packaged) by an insulating encapsulation member 105 such as resin.
Of the three magnetic sensors 103, one is an X-axis magnetic sensor 103x for detecting the terrestrial magnetism in the X-axis direction (the front-back direction or the left-right direction), another is a Y-axis magnetic sensor 103y for detecting the terrestrial magnetism in the Y-axis direction (the left-right direction or the front-back direction), and the other is a Z-axis magnetic sensor 103z for detecting the terrestrial magnetism in the Z-axis direction (the top-bottom direction). These magnetic sensors 103 comprise Hall elements. Semimanufactured substrates 107 are attached to the opposite surfaces from the terminal forming surfaces 106x and 106y of two of the three magnetic sensors 103, the X-axis and Y-axis magnetic sensors 103x and 103y. By attaching side surfaces of these semimanufactured substrates 107 to the upper surface of the circuit substrate 102, the X-axis and Y-axis magnetic sensors 103x and 103y are mounted. The Z-axis magnetic sensor 103z is mounted by directly attaching the opposite surface from the terminal forming surface 106z thereof to the circuit substrate 102.
Therefore, the terminal forming surfaces 106 of the X-axis and Y-axis magnetic sensors 103x and 103y are disposed vertically relative to the upper surface of the circuit substrate 102, and the terminal forming surface 106 of the Z-axis magnetic sensor 103z is disposed horizontally relative to the upper surface of the circuit substrate 102.
That is, the terminal forming surfaces 106 of the X-axis and Y-axis magnetic sensors 103x and 103y are disposed vertically by disposing the semimanufactured substrates 107 upright relative to the upper surface of the circuit substrate 102.
The control semiconductor device 104 is for supplying drive signals to the three magnetic sensors 103 and outputting geomagnetic information of each azimuth detected by each magnetic sensor, and has a computing portion comprising a CPU or an MPU and a storage portion comprising a ROM and/or a RAM with an adequate capacity.
The control semiconductor device 104 is disposed in the center of the upper surface of the circuit substrate 102 of the magnetic azimuth detecting device 101. One of the magnetic sensors 103 is disposed in the center in the longitudinal direction of each of three sides around the control semiconductor device 104.
On the undersurface of the circuit substrate 102 is disposed an external connection electrode used for electrical connection with a device such as a cellular phone in which the magnetic azimuth detecting device is installed.    Patent Document 1: Japanese Unexamined Patent Application Publication No. 2005-114489